Vitamin D status is assessed on plasma or serum levels of its metabolite 25-hydroxyvitamin D [25(OH)D, calcidiol] as it reflects the sum of vitamin D converted in the skin through sunlight exposure and from dietary sources. Several reports advocate that levels <37 nmol/L denote severe vitamin D deficiency; levels <50 nmol/L insufficient; 50-75 nmol/L suboptimal levels and ≥75nmol/L optimal levels (Dawson-Hughes et al, 2005, Huh et al, 2008, Yetley, 2008). In children, most suggested cut-off values for adequate levels of 25(OH)D are based on the absence of rickets, increased measures of bone mineralization and maximal suppression of parathyroid hormone (PTH) levels (Greer, 2009).